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  • Author Author: phoenixcomm
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One of the Best CPU ever made: MC680xx

phoenixcomm

imageIn the late 70's Motorolla, stunned the world with a new CPU family. It was the MK68k family first it was 32-bits internally,  Launched first was the MC68008 which only had an 8-bit external I/O bus. Following the MC68010 was released.  Followed by the MC68012 which included support for virtual memory. Next came the 2nd Generation CPUs MC68020 and MC6830. The MC68040 is a  3rd Generation CPU that was heavily pipelined! Then the 4th Generation emerged the MC68060 which was a supper scaller. 

The processor family was well thought out, from the beginning the MC6000 family had an integer math processor built on the die, but no floating point processors but later the family got two floating point processors MC68881 and later, the MC68882.

The MC68000 family was so successful, in fact, there were multiple computer systems built around the family, Radio Shack TRS-80 Model 16  (Feb 82),  Sun Microsystems Sun-2 (1983),  Apple Mac (1984),  TRS-80 Model 16, and others. 

image image image

The architecture of the MC8000 family was CISC or a Complex Instruction Set Computer, but there were additions. Like in any operation, you can do pre or post-operations like in one clock cycle C, Java, Python, and others. Below is a table that shows the difference between both processors Intel and Motorola.  Now being a C programmer this is neat.  Sorry I can't show the assembler for this, but I worked out to 5 instructions (Intel) vs 1 instruction (MC69000). What does this mean to software performance? Well, how about a for(int a; a <10; a++) with a counter or any other counter for that matter? 

Fins: This processor is in a lot of stuff, and was the favorite of embedded stuff, until recent times. 

INTEL  MOTOROLA

B = TempB - 1
C= TempC - 1
tempA = B + C
A = A + 1

 +A = B- + C-
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  • It was an awesome chip : ) We studied it too, as part of a computer architecture curriculum.

    After uni, I tried making a handheld 68k computer, using the neat "Dragonball VZ" chip (which was a 68k core). I got to the stage of creating a board test program, with a memory monitor to test the RAM/ROM and started writing a first application (which was merely writing its output to a memory buffer pretending to be a screen). This board was used just to test the power supplies, so it's not populated. The 68k chip was at bottom-right of the board, and the other main chips are Flash and SRAM. 

    image

    Everything was an uphill struggle to do solo, there were no ESP32 etc for WiFi, so an external WiFi card was supposed to plug onto the PCMCIA connector in the photo below. The LCD screen was surplus from mobile phones and was only going to be 320x240 or something, but driving that was a pain too (there was no controller, so a CPLD was going to be used with a separate SRAM chip, to offload video refresh from the 68k).

    image 

    I really liked the Freescale/Motorola chips because they had excellent bootloaders, so you could get the initial code for the 68K running over UART, and then push into Flash from there. No fancy JTAG/programmers needed!

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  • It was an awesome chip : ) We studied it too, as part of a computer architecture curriculum.

    After uni, I tried making a handheld 68k computer, using the neat "Dragonball VZ" chip (which was a 68k core). I got to the stage of creating a board test program, with a memory monitor to test the RAM/ROM and started writing a first application (which was merely writing its output to a memory buffer pretending to be a screen). This board was used just to test the power supplies, so it's not populated. The 68k chip was at bottom-right of the board, and the other main chips are Flash and SRAM. 

    image

    Everything was an uphill struggle to do solo, there were no ESP32 etc for WiFi, so an external WiFi card was supposed to plug onto the PCMCIA connector in the photo below. The LCD screen was surplus from mobile phones and was only going to be 320x240 or something, but driving that was a pain too (there was no controller, so a CPLD was going to be used with a separate SRAM chip, to offload video refresh from the 68k).

    image 

    I really liked the Freescale/Motorola chips because they had excellent bootloaders, so you could get the initial code for the 68K running over UART, and then push into Flash from there. No fancy JTAG/programmers needed!

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